Field
The disclosure relates generally to a resonator circuit and, more particularly, to a system with a variable gain amplifier thereof.
Description of the Related Art
It is often required to perform temperature measurements on ICs, system in packages and multi-chip modules, etc, since some components and sub-systems can have temperature dependent performance. These measurements are typically made with a temperature sensitive component or structure like a diode or band gap reference. Voltage reference circuits and oscillators are used in conjunction with semiconductor devices, integrated circuits (IC), and other applications. However, since this will be physically located at a different place on the chip (even if close) and may be made from a different material or material structure, there can exist a phase lag between the actual temperature of the component being monitored and the temperature as measured by the temperature sensor. This phase difference can be particularly problematic during periods of fast temperature transients (e.g. a step change in temperature) as it can result in large mismatches of actual and measured temperatures. If real-time temperature monitoring is required, or in situations where it is not possible to wait until temperature transients have settled (e.g. during production test) it is necessary to devise a solution where the actual temperature of a component can be measured quickly and accurately.
As discussed in U.S. Pat. No. 7,387,435 to Kishi, a temperature sensor is disclosed using a plurality of oscillator/resonator and amplifiers are utilized; a reference signal and signal are compared with a detection circuit. In a temperature sensor, especially in a temperature sensor using a resonator, based on a frequency of one oscillator circuit (resonator), frequencies of the other one or more oscillator circuits (resonators) are measured, and frequency-temperature characteristics of a plurality of resonators are synthesized in order to realize an accurate temperature sensor which does not require an accurate frequency reference regardless of a temperature change, and has a linear characteristic and a wide measurable temperature range. Also, two oscillator circuits have two resonators respectively with quadratic characteristics in which quadratic coefficients are the same and linear characteristics are different from each other, and a difference between oscillation frequencies of both oscillator circuits is obtained.
Oscillators are used to determine pressure and temperature. As discussed in U.S. Pat. No. 5,231,880 to Ward a pressure transducer is disclosed. A plurality of crystals are used to determine both pressure and temperature. A first crystal is used for pressure determination. A second crystal is used for temperature determination. A third crystal is used as a reference. Signals are compared to reference to determine pressure and temperature.
Oscillators are used for determining pressure, and one other property. As discussed in U.S. Pat. No. 5,235,844 to Bonn et al a gas property sensor is disclosed. In this embodiment, a circuit topology includes at plurality of capacitors and inductor to establish a resonant frequency.
In these prior art embodiments, the solution to establish a sensor used a plurality of crystals, or capacitor/inductor pairs utilized various alternative solutions.